Filling the disk hollow following binary black hole merger: The transient accretion afterglow

Journal Article · Fri Jan 15 04:00:00 EST 2010 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.81.024019· OSTI ID:21413388

Shapiro, Stuart L ^[1]

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1. Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)

Tidal torques from a binary black hole empty out the central regions in any circumbinary gaseous accretion disk. The balance between tidal torques and viscosity maintain the inner edge of the disk at a radius r{approx}1.5a-2a, where a is the binary semimajor axis. Eventually, the inspiraling binary decouples from the disk and merges, leaving behind a central hollow (''donut hole'') in the disk orbiting the remnant black hole. We present a simple, time-dependent, Newtonian calculation that follows the secular (viscous) evolution of the disk as it fills up the hollow down to the black hole innermost stable circular orbit and then relaxes to stationary equilibrium. We use our model to calculate the electromagnetic radiation (''afterglow'') spectrum emitted during this transient accretion epoch. Observing the temporal increase in the total electromagnetic flux and the hardening of the spectrum as the donut hole fills may help confirm a binary black hole merger detected by a gravitational wave interferometer. We show how the very existence of the initial hollow can lead to super-Eddington accretion during this secular phase if the rate is not very far below Eddington prior to decoupling. Our model, though highly idealized, may be useful in establishing some of the key parameters, thermal emission features and scalings that characterize this transient. It can serve as a guide in the design and calibration of future radiation-magnetohydrodynamic simulations in general relativity.

• OSTI ID: 21413388
• Journal Information: Physical Review. D, Particles Fields, Journal Name: Physical Review. D, Particles Fields Journal Issue: 2 Vol. 81; ISSN PRVDAQ; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ACCRETION DISKS
AFTERGLOW
BALANCES
BLACK HOLES
CALIBRATION
DECOUPLING
DESIGN
ELECTROMAGNETIC RADIATION
EMISSION
EQUILIBRIUM
EVOLUTION
FIELD THEORIES
GENERAL RELATIVITY THEORY
GRAVITATIONAL WAVES
HARDENING
INTERFEROMETERS
MEASURING INSTRUMENTS
ORBITS
RADIATIONS
RELATIVITY THEORY
SIMULATION
SPECTRA
TIME DEPENDENCE
TORQUE
TRANSIENTS
VISCOSITY
WEIGHT INDICATORS